1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
29 #include "gc_implementation/g1/vm_operations_g1.hpp"
30 #include "gc_implementation/shared/isGCActiveMark.hpp"
31 #include "gc_implementation/g1/vm_operations_g1.hpp"
32 #include "runtime/interfaceSupport.hpp"
33
34 VM_G1CollectForAllocation::VM_G1CollectForAllocation(
35 unsigned int gc_count_before,
36 size_t word_size)
37 : VM_G1OperationWithAllocRequest(gc_count_before, word_size) {
38 guarantee(word_size > 0, "an allocation should always be requested");
39 }
40
41 void VM_G1CollectForAllocation::doit() {
42 G1CollectedHeap* g1h = G1CollectedHeap::heap();
43 _result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded);
44 assert(_result == NULL || _pause_succeeded,
45 "if we get back a result, the pause should have succeeded");
46 }
47
48 void VM_G1CollectFull::doit() {
49 G1CollectedHeap* g1h = G1CollectedHeap::heap();
50 GCCauseSetter x(g1h, _gc_cause);
51 g1h->do_full_collection(false /* clear_all_soft_refs */);
52 }
53
54 VM_G1IncCollectionPause::VM_G1IncCollectionPause(
55 unsigned int gc_count_before,
56 size_t word_size,
57 bool should_initiate_conc_mark,
58 double target_pause_time_ms,
59 GCCause::Cause gc_cause)
60 : VM_G1OperationWithAllocRequest(gc_count_before, word_size),
61 _should_initiate_conc_mark(should_initiate_conc_mark),
62 _target_pause_time_ms(target_pause_time_ms),
63 _full_collections_completed_before(0) {
64 guarantee(target_pause_time_ms > 0.0,
65 err_msg("target_pause_time_ms = %1.6lf should be positive",
66 target_pause_time_ms));
67 guarantee(word_size == 0 || gc_cause == GCCause::_g1_inc_collection_pause,
68 "we can only request an allocation if the GC cause is for "
69 "an incremental GC pause");
70 _gc_cause = gc_cause;
71 }
72
73 void VM_G1IncCollectionPause::doit() {
74 G1CollectedHeap* g1h = G1CollectedHeap::heap();
75 assert(!_should_initiate_conc_mark ||
76 ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
77 (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)),
78 "only a GC locker or a System.gc() induced GC should start a cycle");
79
80 if (_word_size > 0) {
81 // An allocation has been requested. So, try to do that first.
82 _result = g1h->attempt_allocation_at_safepoint(_word_size,
83 false /* expect_null_cur_alloc_region */);
84 if (_result != NULL) {
85 // If we can successfully allocate before we actually do the
86 // pause then we will consider this pause successful.
87 _pause_succeeded = true;
88 return;
89 }
90 }
91
92 GCCauseSetter x(g1h, _gc_cause);
93 if (_should_initiate_conc_mark) {
94 // It's safer to read full_collections_completed() here, given
95 // that noone else will be updating it concurrently. Since we'll
96 // only need it if we're initiating a marking cycle, no point in
97 // setting it earlier.
98 _full_collections_completed_before = g1h->full_collections_completed();
99
100 // At this point we are supposed to start a concurrent cycle. We
101 // will do so if one is not already in progress.
102 bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
103
104 // The above routine returns true if we were able to force the
105 // next GC pause to be an initial mark; it returns false if a
106 // marking cycle is already in progress.
107 //
108 // If a marking cycle is already in progress just return and skip
109 // the pause - the requesting thread should block in doit_epilogue
110 // until the marking cycle is complete.
111 if (!res) {
112 assert(_word_size == 0, "ExplicitGCInvokesConcurrent shouldn't be allocating");
113 return;
114 }
115 }
116
117 _pause_succeeded =
118 g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
119 if (_pause_succeeded && _word_size > 0) {
120 // An allocation had been requested.
121 _result = g1h->attempt_allocation_at_safepoint(_word_size,
122 true /* expect_null_cur_alloc_region */);
123 } else {
124 assert(_result == NULL, "invariant");
125 }
126 }
127
128 void VM_G1IncCollectionPause::doit_epilogue() {
129 VM_GC_Operation::doit_epilogue();
130
131 // If the pause was initiated by a System.gc() and
132 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
133 // that just started (or maybe one that was already in progress) to
134 // finish.
135 if (_gc_cause == GCCause::_java_lang_system_gc &&
136 _should_initiate_conc_mark) {
137 assert(ExplicitGCInvokesConcurrent,
138 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
139
140 G1CollectedHeap* g1h = G1CollectedHeap::heap();
141
142 // In the doit() method we saved g1h->full_collections_completed()
143 // in the _full_collections_completed_before field. We have to
144 // wait until we observe that g1h->full_collections_completed()
145 // has increased by at least one. This can happen if a) we started
146 // a cycle and it completes, b) a cycle already in progress
147 // completes, or c) a Full GC happens.
148
149 // If the condition has already been reached, there's no point in
150 // actually taking the lock and doing the wait.
151 if (g1h->full_collections_completed() <=
152 _full_collections_completed_before) {
153 // The following is largely copied from CMS
154
155 Thread* thr = Thread::current();
156 assert(thr->is_Java_thread(), "invariant");
157 JavaThread* jt = (JavaThread*)thr;
158 ThreadToNativeFromVM native(jt);
159
160 MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
161 while (g1h->full_collections_completed() <=
162 _full_collections_completed_before) {
163 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
164 }
165 }
166 }
167 }
168
169 void VM_CGC_Operation::acquire_pending_list_lock() {
170 // The caller may block while communicating
171 // with the SLT thread in order to acquire/release the PLL.
172 ConcurrentMarkThread::slt()->
173 manipulatePLL(SurrogateLockerThread::acquirePLL);
174 }
175
176 void VM_CGC_Operation::release_and_notify_pending_list_lock() {
177 // The caller may block while communicating
178 // with the SLT thread in order to acquire/release the PLL.
179 ConcurrentMarkThread::slt()->
180 manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
181 }
182
183 void VM_CGC_Operation::doit() {
184 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
185 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
186 TraceTime t(_printGCMessage, PrintGC, true, gclog_or_tty);
187 SharedHeap* sh = SharedHeap::heap();
188 // This could go away if CollectedHeap gave access to _gc_is_active...
189 if (sh != NULL) {
190 IsGCActiveMark x;
191 _cl->do_void();
192 } else {
193 _cl->do_void();
194 }
195 }
196
197 bool VM_CGC_Operation::doit_prologue() {
198 // Note the relative order of the locks must match that in
199 // VM_GC_Operation::doit_prologue() or deadlocks can occur
200 acquire_pending_list_lock();
201
202 Heap_lock->lock();
203 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
204 return true;
205 }
206
207 void VM_CGC_Operation::doit_epilogue() {
208 // Note the relative order of the unlocks must match that in
209 // VM_GC_Operation::doit_epilogue()
210 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
211 Heap_lock->unlock();
212 release_and_notify_pending_list_lock();
213 }